Indicator for brake-pistons



(Nd Model.)

J. J. 'HANNAN. vINDIGATOR FOR BRAKE PISTONS. No. 469,823. I PatentedMar. 1, 189-2.

m mm "ml UNITED STATES PATENT QFFICE.

JAMES J. HANNAN, OF COLUMBUS, OHIO.

INDICATOR FOR BRAKE-PISTONS."

SPECIFICATION forming part of Letters Patent No. 469,823, dated March 1,1892.

Application filed September 1, 1891. Serial No. 404,458. (No model.)

T0 at whom it may concern.-

Be it known that I, JAMES J. HANNAN, of Columbus, county of Franklin,State of Ohio, have invented a certain new and useful Indicator, ofwhich the following is a true and exact description, reference being hadto the accompanying drawings, which form a part of this specification.

My invention relates to a certain improvement in indicators for showingthe extent of the reciprocatory motion. It is designed chiefly as anindicator to show the travel of the piston in an air-brake cylinder, myobject being to so arrange the mechanism that the indicator will alwaysshow the extent of thelast stroke made by the piston. To do this it isof course necessary that the indicator-finger should move backward to or'nearly to the zero-point between each of its forward motlons to thepoint indicating the piston-travel; and it is also necessary that thefinger should remain at the point indicating the pistontravel after thepiston has made a stroke and until it makes another stroke. The deviceby which I have succeeded in filling the above conditions will be bestunderstood as described in connection with the drawings, in which it isillustrated as embodied in simple mechanism, and in which Figure l is aview showing my indicator connected with the piston-rod of an air-brakecylinder. Fig. 2 is a front elevation of the indicator on an enlargedscale; Fig. 3, a similar View withthe front plate of the indicatorcasingremoved; Fig. 4, a cross-sectional plan View taken on the line 1 2 ofFig. 3; Fig. 5, an enlarged sectional view of a portion of the mechanismFig. 6, a view illustrating the same parts as Fig. 5, but showing amodification in the construction of the device and Fig.7, aviewillustrating another modification.

A indicates the framing of a car-platform, to which is attached anair'brake cylinder B, 0 being the piston-rod, R and R a lever-and rodleading to the brakes, (not shown,) S an air-pipe leading to the head ofthe cylinder.

D is the casing containing the mechanism of the indicator; D theface-plate of the said casing, having formed or attached to its face acircular indicator-scale d.

d is an opening in the face-plate.

E is a shaft journaled in the casing and extending out through opening(1 in the faceplate. A shoulder e is formed on the projecting end of theshaft E, and against this shoulder rests the indicator-finger H, whichis clamped against it with sufficient force to make the finger turn withthe shaft when no obstacle is interposed to prevent it. As shown inFigs. 4c and 5, a spring washer I rests upon the top of theindicator-hub, being held in place by the binding-nuts J J.

In the modification shown in Fig.6 aspiral spring 1 rests in an annularcavity formed in thehub of the finger and in a washer I, said washerbeing held in position and the spring under compression by means ofjamnuts J J, as before. G is a pulley loosely journaled on the shaft E,and having a projecting finger g, which extends up so that it willengage with the finger H under proper conditions. 0 is a spring securedto the pulley G and to the casing, and so arranged that it will hold orretain the pulley by resilient pressure to one normal position, thatposition being that which will bring the finger g to the position shownin Fig. 2-that is to say, a position which permits the indicatorfinger Hto point to the zero-mark on the scale.

The parts above described constitute the essential devices of theindicator. In addition to these parts it is only necessary to providemechanism which will simultaneously rotate the shaft E and the pulley Gin opposite directionsthat is to say, which will rotate the pulley Gfrom right to left and the shaft E from left to right, or viceversa-this mechanism being set in operation by the reciprocatorymovement the extent of which the indicator is to show. It is obvious, ofcourse, taking the parts in the position indicated in Figs. 2 and 3,that the rotation of the pulley from right to left will cause the fingerH to make a similar rotative movement, as the finger g is restingagainst it.

The backward movement of the reciprocating object whose movement is tobe indicated permits the pulley G to move back to its initial position;but it does not act upon the shaft E,

and the finger H consequently remains in the 100 position in which itwas left by the action of the finger g, the next outward movement of thereciprocating object, however, causing the shaft E to move from left toright will carry causes it to move forward on the scale to the pointindicating the arc of rotation, made by pulley G and the extent of thereciprocatory movement of the piston or other reciprocating object. Itis obvious of course that thcindicator will not move back to thezeropoint except under the very shortest reciprocatory movements. terialin practice, as under practical conditions the indicator will alwaysmove backward to a point on the scale which indicates less than theminimum stroke of the piston.

Referring again to the drawings,I will now describe the mechanism bywhich I prefer to impart the movements above described to the shaft Eand pulley G. I F is a gear-wheel secured to shaft E; K,a second shaftlying parallel to shaft E and also journaled within the casing. To shaftK is secured a gear-wheel L, which engages with the gear-wheel F andalso a pulley N. It is necessary that the pulley N should engage theshaft, so as to turn with it in one direction, but not necessary that itshould turn backward with the shaft, and therefore I prefer tojournalthe pulley N upon shaft F and to provide a ratchet T and pawl 25, whichwill cause them to engage while the pulley is moving forwardthat is tosay, in the arrangement shown from right to left. P is a cord which ispassed around and secured to the periphery of the pulley G, then engagedwith the pulley N, and then passed out of the indicator-casing andconnected with the reciprocatory part the movement of which is to bemeasured. In the plan shown it is secured to a standard Q, projectingupward from the end of the piston-rod 0. As illustrated in the drawings,the cord P is wrapped around the pulley N, so that it will act upon thepulley by friction. It might, of course, be a sprocketchain, in whichcase the pulley N will be a sprocket-pulley and it would not benecessary that the cord or chain should pass around it. The use of asprocket-chain would be practicable when the ratchet-and-pawldevice-such as is shown in Fig. 7 was used to connect the pulley N andshaft K, but not in the special arrangement shown when the pulley N iskeyed to shaft K, as shown in Fig. 4, although this would be immaterial.were either of the gear-wheels L or F secured to their shafts by thepawl-and-ratchet device.

The operation of the device as a whole is as follows: When thepiston-rod C is thrust out, its connected arm Q draws out the cord P.This cord, being fast to pulley G, causes it to revolve from right toleft, and, being drawn taut around the pulley N, it turns that pulleyand the shaft K in the same direction. The gear L of course turns withshaft K and, engaging with gear F, causes the shaft E toturn in theopposite direction to This, however, is imma that in which the pulley Gis turning. The indicator-finger I-I, being clamped by spring I to shaftE, moves with it backward, or from left to right, until the pin 9 of thepulley G comes in contact with it, when it 1s carried forward by thesaid pin to the full extent of its movement from right to left. As soonas the outward movement of pistonrod 0 is completed, and when it movesback, the cord is drawn back again by the action of the spring 0returning the pulley G to its normal position. The bite of the cordaround pulley N is released, so that the pulley does not turn backwardand the shafts K and E are not moved until the next forward motion ofthe cord. The indicator-finger II therefore remains stationary at thepoint to which it is pushed by pin H until another forward motion of thecord causes shaft E to revolve backward. To guard against any possiblebackward movement which would .disturb the position of theindicator-finger, I prefer to use the pawl-and-ratchet connection, asshown in Fig. '7, so that even if the pulley does turn it will not turnthe shaft upon which it is journaled.

I have shown the device'by which motion is communicated from shaft K toshaft E as a pair of gear-wheels; but it will of course be understoodthat any of the well-known devices for communicating motion in oppositedirections from one shaft to another are the full equivalents of suchgears and may be used without departure from my invention.

Having now described my invention, what I claim as new, and desire tosecure by Letters Patent, is

1. In an indicator, the combination of a shaft E, an indicator-fingerII, mounted on said shaft, but turning with it by frictional contactonly, a pulley G also journaled on said shaft and having a finger 9,adapted to engage the finger H, a spring 0, arranged to hold and returnpulley G to its normal position, and means for simultaneously actuatingthe shaft E and pulley G in opposite directions, all substantially asand for the purpose described.

2. In an indicator, the combination of a shaft E, an indicator-fingerI-I, mounted on said shaft, but turning with it by frictional contactonly, a pulley G also journaled on said shaft and having a finger g,adapted to engage the finger H, a spring 0, arranged to hold and returnpulley G to its normal position, a gear-wheel F, secured to said shaft,a shaft K, a gear-wheel L, secured to said shaft and engaged with gearF, a pulleyN, secured to shaft K, and a cord P, secured to pulley G andoperatively engaged with pulley N, as described.

Witnesses:

H. E. STONEMAN, S. P. BUsH.

- JAMES J. HANNAN.

